1. Field of the Invention
This invention relates to surgical instruments and more particularly to an improved electrosurgical knife.
2. Prior Art
Electrosurgery is a well-known technique in which a high-frequency electrical current is conducted through a surgical instrument into the tissue of a patient to effect electrocoagulation and/or electrocauterization. In electrosurgery, the surgical instrument and the patient are both connected to a source of high-frequency current, and the instrument is provided with a metallic device such as a blade, that functions as an electrode for conducting the high-frequency current to the tissue of the patient. As the surgeon brings the electrode in contact with the tissue, the current passes through the patient to a second electrode connected elsewhere to the body of the patient to complete the current path back to the source of high-frequency current. Because the point of contact between the instrument electrode and the patient is comparatively small, the relative current density and electrical resistance are comparatively high, resulting in electrocoagulation and/or electrocauterization at the point of contact.
One of the advantages of electrosurgery is that it allows the surgeon to perform very exact surgery by touching the electrode blade to the precise area to be treated. A disadvantage of this type of surgery, however, is that the flow of current through the tissue often generates smoke in the vicinity of the electrode. Except in well ventilated areas, the smoke tends to block the view of the surgeon. A more serious concern is that the smoke may be contaminated with viruses from the patient which may be transmitted to anyone who inadvertently inhales the smoke. To protect the medical staff from exposure to the virus of deadly or crippling diseases, it is important to aspirate the smoke from the immediate surgical area before it dissipates into the air breathed by the attendants. To solve this problem, it is sometimes necessary to have a separate attendant hold an aspiration tube adjacent the electrode while the surgeon is performing the operation. The disadvantages of such an arrangement are obvious. The electrosurgical technique may be used for sealing off blood vessels and hence, the surgeon may be required to operate in an area where blood tends to accumulate and particulates may be collected. Accordingly, it is desirable to have a means for removing accumulated blood and particulates as well as smoke from the surgical area. In an analogous fashion, some surgical procedures may require an additional source of light so that the surgeon may be able to adequately view the area to be treated, while in other situations no such additional light is required.
Examples of patents disclosing prior art electrosurgical instruments are as follows:
U.S. Pat. No. 3,828,780 to C. F. Morrison, Jr. (dated Aug. 13, 1974) describes a combined electrosurgical and suction instrument. The instrument consists essentially of an elongated body having a hollow metal tube with a distal end functioning as the electrode and having a proximal end connected to an electrical wire in the housing. Suction is applied to the proximal end of the hollow metal tube so as to remove fluids through the tube electrode.
U.S. Pat. No. 3,825,004 to J. G. Durden III (dated Jul. 23, 1974) discloses a disposable electrosurgical cautery having a handle constructed of upper and lower halves forming a cavity for accommodating a hollow metal tube. The distal end of the tube is used as the electrode and the proximal end is connected to an electrical wire and a vacuum hose to withdraw fluids through the tube electrode.
U.S. Pat. No. 3,906,955 to R. R. Roberts (dated Sep. 23, 1975) discloses an electrosurgical tool having a housing with an electrode disposed at the distal end of the housing and connected to electrical wiring within the housing. A separate vacuum tube contained within the housing and extending beyond the distal end of the housing is disposed adjacent the electrode to withdraw fluid from the cutting area. The housing is provided with a manually-operable slide which is rigidly attached to the vacuum tube internal to the housing and which may be used to position the distal end of the vacuum tube within the range of travel of the manually-operable slide.
U.S. Pat. No. 3,974,833 to J. G. Durden III (dated Aug. 17, 1976) discloses a surgical knife with a combination cutting electrode and vacuum tube such as that disclosed in U.S. Pat. No. 3,825,004 referenced above, and is further provided with an aperture in the knife handle communicating with an opening in the vacuum tube. By selectively covering the aperture in the handle with a finger, the surgeon controls the amount of suction applied to the surgically treated area.
U.S. Pat. No. 4,562,838 to W. S. Walker (dated Jan. 7, 1986) discloses an electrosurgical knife having a generally cylindrical housing and an electrode extending from a central opening in the housing at the distal end thereof. The housing is provided with a number of ducts at the distal end thereof in communication with a cavity internal to the housing. A hose, which may be either connected to a sterile air-pressure source or a vacuum source, is connected to the fluid cavity within the housing and may be used to aspirate smoke or to distribute an airflow in the area of the surgical blade. The housing is further provided with a mounting channel along its upper edge for slidably receiving a light-transmitting cable of a fiber-optic system to illuminate the region around the cutting blade.
Disadvantages of these and other prior art devices are that the electrosurgical knives have become relatively bulky and complex structures which are not inexpensive to manufacture. The prior art devices are often difficult to hold and lack the flexibility that is desired by many surgeons. Surgeons in a number of hospitals use the less expensive standard electrosurgical knives which do not have the aspirating capability or a separate light source to perform operations in well-ventilated and well-lighted areas, and use the more expensive, specialized knives only when required. This means that the hospitals must have multiple inventories. It is therefore desirable to provide a surgical knife which is inexpensive and optionally provides the capabilities of the more specialized knives.
A particular disadvantage of prior art electrosurgical knives is the inability to withdraw smoke and other fluid and particulates from the immediate vicinity of the electrode when electrodes of different types and lengths are used. The distance of the electrode from the knife handle may vary greatly, e.g., from approximately 1 inch to over 12 inches. The shape of the electrodes may be that of a tube, a flat blade, a loop, a needle, or other configurations. Prior art devices do not provide an electrosurgical knife which is readily adaptable to provide aspiration at the surgical contact area for the various electrodes used in electrosurgery.